Suppressors or so-called silencers for firearms generally operate to reduce the energy of the gases propelling the bullet from the muzzle of the firearm. By reducing the energy level of the propellant gases in a relatively controlled manner compared to the abrupt discharge of gases leaving the muzzle of an unsuppressed firearm, the audible noise or sharp report of the firing can be suppressed to a significant extent. One technique of suppressing the report of firearms calls for reducing the temperature of the propellant gases, before these gases are released to the atmosphere. Since the internal energy of a compressed gas is a function of the gas temperature, the energy of propellant gases exiting the suppressor at a reduced temperature thus is reduced, bringing about a corresponding reduction in the noise produced by the propellant gases.
Various kinds of suppressors seeking to accomplish the foregoing function are known to the prior art. A number of practical disadvantages generally are associated with these prior suppressors. For example, some suppressors require expansion chambers, baffle plates, partitions, or the like, machined or otherwise fabricated in a manner requiring relatively costly fabrication and assembly techniques. Because suppressors generally are attached to the muzzle of a firearm and extend a distance in front of the muzzle, the added diameter and weight of such existing suppressors frequently is another disadvantage.
One such suppressor, disclosed in U.S. Pat. No. 2,448,382, seeks to reduce these problems by providing the suppressor concentric with a portion of the rifled barrel of the firearm. Radial holes are drilled through the rifled barrel to vent the propellant gases into the surrounding suppressor. This arrangement, while reducing the overall length of firearm-suppressor combination, adversely affects the accuracy of the firearm unless the radial holes enter the rifled barrel only in the grooves of the rifling. This desired placement of the radial holes, while not impossible, calls for considerable manufacturing precision and thus is impractical.